83. About Sources for Plug-Ins
If you have specific functionality that you need but that Acrobat does not provide, a third-party plug-in solution is probably available on the Web. Most plug-ins must be purchased before downloading them. However, some websites allow you to download a trial version of the plug-in that either has limited functionality or expires after a set number of days.
A huge assortment of plug-ins is available for Acrobat. For a broad selection of popular plug-ins from various developers, we recommend visiting the Acrobat plug-in page of the official Adobe website at http://store.adobe.com/store/products/plugins/. Other good sources for Acrobat plug-ins and information include the PDF Store (http://www.pdfstore.com); Planet PDF (http://www.planetpdf.com/); The World-Wide Power Company, LLC (http://www.thepowerco.com/); and PluginsWorld (http://pluginsworld.com). On each of these sites, you can find plug-ins from many manufacturers.
For example, The World-Wide Power Company, LLC offers an auto-save plug-in that automatically saves your PDF as you're working. PluginsWorld offers a plug-in that enables you to erase content from your PDF.